The present invention relates to an electronic switch with a MOSFET and a bipolar transistor, in which the collector-emitter section of the bipolar transistor and the drain-source section of the MOSFET are connected in series.
Such a switch has been described, for example, in the periodical "Elektronik," 23/1981, pages 93 to 96. This circuit takes into account the fact that MOSFETs which handle large voltages, for example, those of over 300 V have a relatively high on-state DC resistance R.sub.on. The combination of bipolar transistor and a MOSFET makes it possible to use a MOSFET designed to handle low voltages with a low on-state DC resistance and a high voltage bipolar transistor, with an on-state DC resistance which is lower than that of a MOSFET with a corresponding voltage handling capability. The disadvantage of the series circuit described above is due to the fact that a separate source of DC voltage is required for the bipolar transistor, or else a capacitor that is dynamically charged through a transformer and whose capacity must be attuned to the clock frequency of the switch must be used, in order to prevent saturation of the bipolar transistor.